Đáp án:
AB=560km
Giải thích các bước giải:
\(\begin{array}{l}
1.\\
{t_1} = \frac{{AB}}{{{v_1}}} = \frac{{AB}}{{15}}\\
{t_2} = \frac{{AB}}{{{v_2}}} = \frac{{AB}}{{30}}\\
t = {t_1} - {t_2}\\
t = \frac{{AB}}{{15}} - \frac{{AB}}{{30}}(1)\\
{t_1}' = \frac{{AB + 10}}{{{v_1}}} = \frac{{AB + 10}}{{15}}\\
{t_2}' = \frac{{\frac{{AB}}{2}}}{{{v_2}}} + \frac{{\frac{{AB}}{2} + 10}}{{{v_2} - 3}} = \frac{{\frac{{AB}}{2}}}{{30}} + \frac{{\frac{{AB}}{2} + 10}}{{30 - 3}} = \frac{{AB}}{{2.30}} + \frac{{\frac{{AB}}{2} + 10}}{{27}}\\
t = {t_1}' - {t_2}'\\
t = \frac{{AB + 10}}{{15}} - \frac{{AB}}{{2.30}} - \frac{{\frac{{AB}}{2} + 10}}{{27}}(2)\\
(1),(2) \Rightarrow \frac{{AB}}{{15}} - \frac{{AB}}{{30}} = \frac{{AB + 10}}{{15}} - \frac{{AB}}{{2.30}} - \frac{{\frac{{AB}}{2} + 10}}{{27}}\\
AB = 560km\\
\end{array}\)